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Zero thermal expansion in cubic MgZrF 6
Author(s) -
Xu Jiale,
Hu Lei,
Song Yuzhu,
Han Fei,
Qiao Yongqiang,
Deng Jinxia,
Chen Jun,
Xing Xianran
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15105
Subject(s) - thermal expansion , raman spectroscopy , negative thermal expansion , isotropy , lattice (music) , fluorine , atmospheric temperature range , thermal , crystal structure , materials science , transverse plane , chemistry , condensed matter physics , analytical chemistry (journal) , crystallography , thermodynamics , optics , composite material , physics , organic chemistry , structural engineering , acoustics , engineering , metallurgy
Isotropic zero thermal expansion ( ZTE ) is rare but intriguing physical property in materials. Here, we report an isotropic ZTE property in a double ReO 3 ‐type compound of MgZrF 6 , which exhibits a negligible value of coefficient of thermal expansion (α l = −7.94 × 10 −7 K −1 ( XRD ), α l = −4.22 × 10 −7 K −1 (dilatometry), 300‐675 K). The ZTE mechanism of MgZrF 6 is understood by the joint studies of temperature dependence of crystal structure and lattice dynamics. Interestingly, different magnitudes of atomic displacement parameters ( ADP s) for the fluorine atoms in M Z rF 6 ( M = Ca, Ni, Mg) are found. The strong temperature sensitivity of ADP s demonstrates intensive transverse thermal vibration of fluorine atoms, which contributes essentially to the negative thermal expansion of CaZrF 6 . By contrast, for NiZrF 6 with positive thermal expansion, the temperature response of ADP s is weak. Moderate transverse thermal vibration takes place in MgZrF 6 , and ZTE appears. Furthermore, lattice dynamics of MgZrF 6 is studied by temperature‐dependent Raman spectroscopy, which reveals the ZTE mechanism. In particular, the F 2g and A g modes, corresponding to the bending and stretching vibrations of fluorine atoms, respectively, neither soften nor harden over the whole temperature range, which is correlated with the isotropic ZTE property of MgZrF 6 .